Fin deployment system

Abstract

A projectile having a fin deployment system disposed about its circumference. The fins are initially contained by a fin cover that is removed by aerodynamic force. The fins are then rotated around a rotational axis parallel to and offset from the central axial axis of the projectile body by the centrifugal forces created by the rotation of the projectile as the projectile passes through a barrel of a gun system or tube launcher. The fin deployment system can also have locking systems that lock the fins in the deployed position and prevent the fins from rotating back into the retracted position after deployment.

The invention claimed is: 
     
       1. A fin deployment system for a projectile comprising
 a plurality of fins rotatable along a rotational axis parallel to and offset from the central axial axis of a projectile body, wherein each fin is rotatable around the rotational axis between a retracted position and a deployed position, rotation to the deployed position occurs only from the centrifugal forces generated by the spinning of the projectile; 
 a cylindrical mount assembly defining a plurality of axial channels each aligning with the offset rotational axis of a corresponding fin; said cylindrical mount assembly having a solid interior face for defining a central opening and wrapping around the circumference of the aft end of the projectile so that the cylindrical mount assembly remains independent of the projectile; 
 a fin cover positioned over the fins and cylindrical mount assembly when the fins are positioned in the retracted position, and wherein the fin cover slidably engages the cylindrical mount so that as the projectile exits a tube or a gun barrel, aerodynamic drag separates the fin cover from the projectile; said fin cover having a tubular shape so as not to block the aft end of the projectile; and 
 wherein said fin cover completely covers each fin to prevent rotation of the barrel within the axial channel until the fin cover is removed and the fin cover includes axial indentations on an outer face for placement of a vent to equalize the pressure between the fin cover and the cylindrical mount assembly during operation. 
 
     
     
       2. The fin deployment system of  claim 1  wherein the offset rotational axis is proximate to the exterior of the projectile body such that each fin can be rotated into the retracted position, wherein the fin is generally aligned with or contoured to follow the exterior of the projectile body when positioned in the retracted position. 
     
     
       3. The fin deployment system of  claim 1  wherein each fin comprises a fin portion and a barrel portion at one end of the fin portion and rotatable within the axial channel between the retracted position and the deployed position. 
     
     
       4. The fin deployment system of  claim 3  wherein the fin deployment system can further comprise a locking ring defining a plurality of engagement surfaces corresponding to each of the axial channels. 
     
     
       5. The fin deployment system of  claim 4  wherein each fin can comprise a drive axle extending through the barrel of the fin, wherein the locking ring defines a first plurality of ports each corresponding to one of the plurality of axial channels and adapted to rotatably receive one end of the drive axle. 
     
     
       6. The fin deployment system of  claim 5  wherein the fin deployment assembly can further comprise a secondary ring positioned opposite the locking ring against an opposite end of the cylindrical mount assembly, said secondary ring defines a second plurality of ports each corresponding to one of the plurality of axial channels and adapted to rotatably receive the opposite end of the drive axle. 
     
     
       7. The fin deployment system of  claim 3  wherein the barrel portion of the fin can comprise a protrusion or define a cutout that is rotated into engagement with a stop protrusion when the fin is rotated into the deployed position, said stop protrusion is positioned to engage the fin portion and stop the rotation of the fin when the fin portion is positioned in a plane transverse the central axis of the projectile, thereby preventing over rotation of the fin portion and maintaining a proper spacing of the deployed fins. 
     
     
       8. The fin deployment system of  claim 3  wherein the barrel of each fin can define a cutout portion providing an engagable locking surface so that each axial channel defines a groove that aligns with the cutout portion when the barrel is rotated into the deployed position. 
     
     
       9. The fin deployment system of  claim 8  wherein the cylindrical mount assembly further comprises a locking tab with a corresponding spring positioned within each groove so that upon rotation of the fin into the deployed position and the alignment of the cutout portion with the groove, the spring is biased to push the locking tab out of the groove such that locking tab at least partially protrudes from the groove and engages the locking surface to prevent the fin from rotating back to the retracted position. 
     
     
       10. The fin deployment system of  claim 1  wherein the fin cover can comprise at least one vent for equalizing the pressure of any air contained within the fin cover with atmospheric pressure as the projectile leaves the barrel or tube launcher. 
     
     
       11. A projectile comprising a projectile body and a fin deployment system, said fin deployment system comprising;
 a plurality of fins; 
 a cylindrical mount assembly having a tubular shape with an outer surface and an inner surface, the inner surface being a uniform face without need for openings or interaction with the projectile body, 
 wherein each fin further comprises a fin portion and a barrel positioned at one end of the fin portion such that rotation of the barrel rotates the fin portion around the rotational axis of the barrel, the rotation of the fins created only by the centrifugal force of the rotating projectile; 
 wherein the outer face of the cylindrical mount assembly defines a plurality of axial channels each corresponding to one of the fins and adapted to rotatably receive the barrel of the corresponding fin; and 
 a fin cover positioned completely over the fins, said fin cover having a tubular shape and slidably engaging the cylindrical mount assembly, said fin cover separating from the fin deployment system due to aerodynamic forces experienced by the fin cover after launch from a gun barrel or tube; 
 wherein said fin cover completely covers each fin to prevent rotation of the barrel within the axial channel until the fin cover is removed and the fin cover includes axial indentations on an outer face for placement of a vent to equalize the pressure between the fin cover and the cylindrical mount assembly during operation. 
 
     
     
       12. A method of deploying a plurality of fins from a tube or barrel launched projectile, the method comprising:
 mounting a cylindrical mount assembly about the circumference of the aft end of the projectile, said cylindrical mount assembly including a plurality of fins, wherein the fins are rotatable along a rotational axis offset from a projectile central axis, the cylindrical mount assembly including all the necessary structure for maintaining and rotating the fins to a deployed position so as not to require structure within the projectile; 
 rotating the fins into a retracted position such that the fins are generally aligned tangential with the exterior of the projectile body; 
 fitting a removable fin cover over the cylindrical mount assembly, said fin cover holding the plurality of fins in the retracted position, wherein said fin cover completely covers each fin to prevent rotation of the barrel within the axial channel until the fin cover is removed and the fin cover includes axial indentations on an outer face for placement of a vent to equalize the pressure between the fin cover and the cylindrical mount assembly during operation; 
 firing the projectile from a tube or barrel, wherein the barrel or tube rotates the projectile body around the central axis; 
 removing the fin cover after the projectile leaves the tube or barrel by aerodynamic forces experienced by the fin cover after launch from the tube or barrel; and 
 deploying the fins by the rotation of the projectile. 
 
     
     
       13. The method of deploying a plurality of fins according to  claim 12  further including locking the fins in a deployed position, wherein said deployed position is generally in a plane transverse the central axis of the projectile, said cylindrical mount assembly comprising the locking mechanism. 
     
     
       14. The method of deploying a plurality of fins according to  claim 12  wherein aerodynamic drag separates the fin cover from the projectile. 
     
     
       15. The method of deploying a plurality of fins according to  claim 12  wherein the fin cover includes at least one vent for equalizing the pressure of any air contained within the fin cover with atmospheric pressure as the projectile leaves the barrel or tube launcher. 
     
     
       16. The method of deploying a plurality of fins according to  claim 12  wherein each fin comprises a fin portion and a barrel portion at one end of the fin portion and said fin rotatable between the retracted position and the deployed position. 
     
     
       17. The method of deploying a plurality of fins according to  claim 16  wherein the rotation of the projectile imparted by the rifling of the barrel or tube creates centrifugal forces causing the barrel of each fin to rotate the fin portion until the fin portion extends axially outward from the central rotational axis of the projectile upon exiting the muzzle of the barrel. 
     
     
       18. The method of deploying a plurality of fins according to  claim 12  further including rotating the projectile body by an air scoop shaped to create axial rotation of the projectile. 
     
     
       19. The method of deploying a plurality of fins according to  claim 12  further including rotating the projectile body by angling a rocket exhaust, said rocket exhaust provided by a rocket disposed within the projectile body.